How does Knowledge Pool + Teferi lock work with the stack?
Asked by JMurd117 6 years ago
So I know that Knowledge Pool + Teferi, Mage of Zhalfir is a lock cause the opponents cant cast spells at instant speed anymore. My question is about how Knowledge Pool stacks. When a player casts a spell, Knowledge Pool goes on the stack and is about to exile the spell they cast. What happens when that ability resolves? Is the stack empty? Or is there an object on the stack that is telling the player to pick a different spell exiled under Knowledge Pool? I need help for explaining the lock to people when they arent familiar with the lock as I am still not 100% of how the stack looks when the ability resolves.
Gidgetimer says... #2
The simple explanation is that can't overrides can and you can not cast a sorcery during the resolution of an ability therefore even though Knowledge Pool tells you that you can cast a spell as the trigger resolves, Teferi, Mage of Zhalfir checks to see if you could normally cast a sorcery at this time and sees no so will not allow opponents to cast off of knowledge pool.
Neotrup says... Accepted answer #1
As the ability of Knowledge Pool resolves it is on the stack. It exiles the spell it references (which is below it on the stack) and allows that spells controller to cast another nonland card that was exiled. This ignores timing restrictions as it is allowing a player to cast a spell as part of the ability's resolution. Teferi, Mage of Zhalfir prevents opponents from ignoring timing restrictions, so opponent's can't actually cast a spell during the abilities resolution. Then the ability leaves the stack as it's done as much as it can, and as it exiled the spell that triggered it the stack is now likely empty. Without Teferi, Mage of Zhalfir instead the new spell would be placed on the top of the stack, meaning that Knowledge Pool's ability is no longer the topmost object on the stack, but that's fine as it already started resolving. Then it would be removed from the stack and there would be a new spell so the stack would not be empty.
March 22, 2018 4:17 p.m.